For example, in treatments of an exhaust gas containing VOCs (such as volatile alcohols, ketones, esters, ethers, aldehydes, and aromatic compounds), a method of honeycomb rotor TSA (temperature swing adsorption method)+catalytic combustion method is most frequently adopted. In this method, the VOCs contained in an exhaust gas are supplied into an adsorption bed packed with a high silica zeolite to be adsorbed and removed, a high-temperature hot blast is supplied into the adsorption bed of the high silica zeolite to which the VOCs are adsorbed to detach the VOCs at a high temperature, the VOCs are concentrated by volume reduction, and the detached/concentrated VOCs are subjected to oxidative decomposition through catalytic combustion. In addition, the treatments that are expected to be wide-spread in the future include a Packed Bed Plasma VOC Treatment, which is proposed by U.S. Environmental Agency, in which life-prolonging discharge is performed at a surface of a ferroelectric substance in a packed bed packed with the ferroelectric substance (such as barium titanate), and a VOC-containing gas is then supplied into the packed bed to perform oxidative decomposition. These methods show constant performance in the treatments of the VOCs, but in the method of honeycomb rotor+catalytic combustion, there is a limit to cost reduction due to the complexity of apparatuses and the complexity of operations, and in the Packed Bed Plasma VOC Treatment, there is a limit to the VOC removal rate, so that there is concern that these methods will not be able to conform to the emission regulations for the VOCs and malodorous components in the future.
On the other hand, performing oxidative decomposition of the VOCs through homogeneous gas phase reaction by adding an ozone gas to a gas containing contamination components such as the VOCs and the malodorous components (hereinafter, description will be made taking the VOCs as a representative example) is also possible. However, such oxidative decomposition has not been put into practical use yet because the ozone oxidation reaction of the VOCs in low concentrations is slow; the treatment of unreacted ozone is complex; and the production cost of ozone that is used as an oxidizing agent is expensive. In addition, there is proposed a method in which a high silica adsorbent co-adsorbing the VOCs and ozone is used as a packing material for improving the reaction efficiency in the ozone oxidation, thereby achieving enhancement of efficiency in the oxidation reaction of the VOCs by ozone in a crystal of the high silica adsorbent which has co-adsorbed the VOCs and ozone (see Patent Literatures 1 and 2, and the like).